Liquid crystal display device having particular sealing structure

ABSTRACT

A liquid crystal display device comprises a TFT substrate, forming a wiring made of a material shutting off UV rays on a peripheral region thereof, and a sealing layer, including a UV ray curable resin therein, and being formed on peripheral regions of the substrate, to enclose the liquid crystal layer. The wiring and the sealing layer formed on the peripheral region are so provided that they are put on each other, at least in part thereof, on the wiring are provided plural numbers of opening portions formed in region where the wiring and the sealing layer are put on each other, and the opening portions are divided into a first area beside a display region and a second area outside the first area, and an opening ratio of the opening portions of the first area is larger than the opening ratio of the opening portions of the second area.

CLAIM OF PRIORITY

The present application claims priority from Japanese patent applicationJP2012-134364 filed on Jun. 14, 2012, the content of which is herebyincorporated by reference into this application.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a liquid crystal display device,applying a sealing member including an ultraviolet ray curable resintherein, and in particular, relates to a liquid crystal display device,improving durability thereof against an external force, such as, slidingand/or pressure, etc., when being applied with polishing thereon, withencouraging curing of the seal.

2. Description of the Related Art

As a method for forming a liquid crystal layer between a TFT substrateand a substrate facing thereto (hereinafter, a facing substrate), in theliquid crystal display device, an ODF (One Drop Fill) method has beendeveloped. In this method, a sealing layer is formed on the peripheralregion of a substrate, to drop a liquid crystal within a frame of thesealing layer, and the TFT substrate and the facing substrate are piledup on each other, and thereby sealing the liquid crystal therein. As amaterial of the sealing member is applied a UV (ultra-violet) curabletype resin or a concomitant type resin, combining the UV curable resinand a heat curable resin, and it is cured through irradiation of UV raysafter lamination of those two pieces of substrates.

On the other hand, with the liquid crystal display device, there areprovided wirings, such as, a common wiring, etc., on the peripheralportion of the TFT substrate. Due to a demand of sizing small andnarrowing the frame of the liquid crystal display device, the wiringsprovided on the peripheral portion and the sealing layer for sealing theliquid crystal layer are disposed to be piled up on each other. However,in general, the wirings shut off the lights, and then curing of thesealing layer through irradiation of the UV rays comes to beinsufficient.

Then, in the Japanese Patent Application Laid-Open Publication No.2010-204417 is described a technology for curing the sealing agent in ashort time-period, with high efficiency, with provision of an openingfor use of passing the UV rays therethrough upon the wiring on theperiphery, in the liquid crystal display device, forming the sealinglayer of the photo curable type resin or the concomitant type resin, onthe peripheral region, and having the wirings of a material, which shutsoff the UV rays on the peripheral region of the substrate (please seethe second embodiment thereof).

SUMMARY OF THE INVENTION

In the Japanese Patent Application Laid-Open Publication No.2010-204417, as is shown in FIG. 14 and FIG. 15 thereof, the openings 19for use of passing the UV rays therethrough are provided on both sidesalong a side portion of the wiring 13, i.e., in places on both sides ofthe sealing layer. However, with such structure of this opening, thecuring of the sealing is not always sufficient. If the curing of sealingof the sealing layer is short, then for example, this results shortageof durability against the external force, such as, sliding and/orpressure, etc. For this reason, a column-like spacer on a surface of thefacing substrate and the wirings on a surface of the TFT substrate rubon each other, so that cutting of an alignment film is generated on thecolumn-like spacer and the wiring; i.e., generating a defect of minutebright spot on a screen.

Also, if enlarging an opening ratio of the wiring, there would begenerated a problem of increasing the resistance of the wiring. Suchincrease of resistance of the wiring brings about a possibility ofbadness in the display, a lowering of quality of display, and/orbreakdown of wires, etc. For example, in case where the resistance of acommon wire increases, common electric potential of a specific pixelcannot converge within a gate selection time; i.e., there is apossibility of problems, such as, changing of the degree of whiteness ona specific display pattern, or coloring, etc.

The present invention, accomplished for dissolving such problems, has anobject to provide a liquid crystal display device having durabilityagainst the external force, such as, sliding and/or pressure, i.e., amechanical polishing. Also, in addition thereto, it has an object ofsuppressing the increase of the wiring resistance down to the minimum.

For dissolving such problem(s) as mentioned above, if listing up anexample of the liquid crystal display device, there is provided a liquidcrystal display device, comprising: a TFT substrate, having pixelelectrodes and TFTs thereon and forming a wiring made of a materialshutting off UV rays on a peripheral region thereof; a facing substrateto be disposed to face the TFT substrate; a liquid crystal layer putbetween the both substrates; and a sealing layer, including a UV raycurable resin therein, and being formed on peripheral regions of theboth substrate, to enclose the liquid crystal layer, wherein the wiringand the sealing layer formed on the peripheral region are so providedthat they are put on each other, at least in part thereof, on the wiringare provided plural numbers of opening portions formed in region wherethe wiring and the sealing layer are put on each other, and the openingportions are divided into a first area beside a display region and asecond area outside the first area with respect to the display region,and an opening ratio of the opening portions of the first area is largerthan the opening ratio of the opening portions of the second area.

Also, according to the present invention, in the liquid crystal displaydevice, as described in above, preferably, the opening ratio of theopening portions of the first area is 30 to 80%, while the opening ratioof the opening portions of the second area is 5 to 50%, more preferably,the opening ratio of the opening portions of the first area is 50 to70%, and more preferably, the opening ratio of the opening portions ofthe second area is 5 to 30%.

If listing up other example of the liquid crystal display device, thereis also provided a liquid crystal display device, comprising: a TFTsubstrate, having pixel electrodes and TFTs thereon and forming a wiringmade of a material shutting off UV rays on a peripheral region thereof;a facing substrate to be disposed to face the TFT substrate; a liquidcrystal layer put between the both substrates; and a sealing layer,including a UV ray curable resin therein, and being formed on peripheralregions of the both substrate, to enclose the liquid crystal layer,wherein the wiring and the sealing layer formed on the peripheral regionare so provided that they are put on each other, at least in partthereof, on the wiring are provided plural numbers of opening portionsformed in region where the wiring and the sealing layer are put on eachother, and an opening ratio of the opening portion is 30 to 80%.

Also, if listing up further other example of the liquid crystal displaydevice, there is also provided a liquid crystal display device, a TFTsubstrate, having pixel electrodes and TFTs thereon and forming a wiringmade of a material shutting off UV rays on a peripheral region thereof;a facing substrate to be disposed to face the TFT substrate; a liquidcrystal layer put between the both substrates; and a sealing layer,including a UV ray curable resin therein, and being formed on peripheralregions of the both substrate, to enclose the liquid crystal layer,wherein the wiring and the sealing layer formed on the peripheral regionare so provided that they are put on each other, at least in partthereof, and on the wiring, plural numbers of opening portions areprovided in a region where the wiring and the sealing member are put oneach other, and in an inside of the sealing layer.

With the present invention mentioned above, since a transmission factorfor the UV rays is increased in the wiring portions, then curing of aseal of the sealing layer is promoted; therefore, rubbing between thecolumn-like spacer and the TFT wiring can be suppressed, when receivingthe external force of the sliding and/or the pressure, etc., i.e., themechanical polishing thereon, and therefore it is possible to preventthe alignment film from being cut out.

Also, with making the opening ratio on the wiring in the second areasmaller than that in the first area, which lies outside than the firstarea with respect to the display region, it is possible to suppress anincrease of the resistance of the wiring down to the minimum.

BRIEF DESCRIPTION OF THE DRAWINGS

Those and other objects, features and advantages of the presentinvention will become more readily apparent from the following detaileddescription when taken in conjunction with the accompanying drawingswherein:

FIG. 1 is a plane view of a corner portion of a liquid crystal displaydevice, according to an embodiment 1 of the present invention;

FIG. 2 is a cross-section view of the corner portion of the liquidcrystal display device, according to the embodiment 1 of the presentinvention;

FIG. 3 is a view for showing manufacturing processes of the liquidcrystal display device, into which an ODF process is applied;

FIG. 4 is a plane view for showing the structures of the liquid crystaldisplay device, briefly;

FIG. 5 is a plane view of the corner portion of the liquid crystaldisplay device, according to a comparative example;

FIG. 6 is a cross-section view of the corner portion of the liquidcrystal display device, according to the comparative example;

FIG. 7 is a plane view of a corner portion of a liquid crystal displaydevice, according to an embodiment 2 of the present invention;

FIG. 8 is a cross-section view of the corner portion of the liquidcrystal display device, according to the embodiment 2 of the presentinvention; and

FIG. 9 is a view for explaining an opening ratio.

DETAILED DESCRIPTION OF THE INVENTION

Hereinafter, embodiments according to the present invention will befully explained by referring to the attached drawings. In each drawing,the same numeral references will be given to the same constituentelements, as far as possible, and repetitive explanations thereof willbe omitted.

Before explaining the embodiments, an explanation will be given on anoutline of the liquid crystal display device.

FIG. 3 shows a flow of processes for forming liquid crystal displaycells, into which the ODF process is applied, being a target of thepresent invention. After applying an alignment film on a TFT substrate,which forms TFTs (Thin Film Transistors) and/or pixel electrodesthereon, with using a printing method or an inkjet method (S101), analignment film is formed for aligning a liquid crystal, according to arubbing method or a photo-alignment method (S102), and then a liquidcrystal is dropped (S103). Similarly, after applying the alignment filmon the facing substrate forming a color filter (CF) thereon, through theprinting method or the inkjet method (S104), an alignment film is formedfor aligning a liquid crystal, according to a rubbing method or aphoto-alignment method (S105), and then a sealing material is appliedthereon (S106). And, liquid crystal display cells are formed bylaminating the TFT substrate, on which the liquid crystal is dropped, onthe facing substrate, on which the sealing material is applied (S107).Thereafter, in a step S108 is irradiated ultraviolet (UV) rays thereuponand in a step S109 is conducted a heating process thereon, then thesealing material is cured. And, in a step S110, the substrate is cut outand separated, and then each liquid crystal cell is manufactured. Thoughnot shown in the figure, there are cases of introducing a step ofmechanically polishing the substrate to be thin, before the step ofcutting (S110). Further, in the steps S103 and S106, the sealingmaterial may be applied on the TFT substrate and the liquid crystal maybe dropped on the facing substrate, or on both substrates may beconducted the application of the sealing agent and the drop of theliquid crystal. The sealing material to be applied in the presentinvention may be one, which can be cured through the irradiation of theUV rays thereon, such as, the UV curable type resin or the concomitanttype resin, combining the UV curable resin and the heat curable resin,for example.

FIG. 4 is a plane view for showing the structures of the liquid crystaldisplay device, briefly. The TFT substrate 10 and the facing substrate20 are adhered with, by means of the sealing member provided on theperipheral region of the substrate. Inside the sealing member 30 isformed a display region 40. In the display region 40 of the TFTsubstrate 10 are formed pixel electrodes, in a matrix manner. In thedisplay region 40 of the facing substrate 20 are formed color filterscorresponding to the pixels of the TFT substrate 10.

Up to a terminal portion 15 of the TFT substrate 10 are drown outwirings, such as, a gate wiring, a source wiring, etc., to be connectedwith a driver 25. From this driver 25 is drawn out a common wiring 50,and it is formed in a panel periphery portion.

First Embodiment

FIG. 1 is an enlarged view of the panel periphery portion of anembodiment 1, corresponding to a corner portion shown in FIG. 4. Also,FIG. 2 is a cross-section view of the panel periphery portion of theembodiment 1, in the direction shown by an A-A′ line in FIG. 1. On thepanel periphery portion is formed the common wiring 50, and it isdisposed at a position piling on the sealing member 30 mentioned above.On the common wiring 50 are formed opening portions 53A and 53B, forletting the UV rays 60 to pass therethrough, so as to cure the sealingmaterial, in the region lying on the sealing member 30. The openingportions 53A are formed in a first area 55A beside the display region,while the opening portions 53B are formed in a second area, which liesoutside than the first area with respect to the display region. In thepresent embodiment, an opening ratio of the opening portion 53A, whichis formed beside the display region, is determined to be larger than theopening ratio of the opening portion 53B, which is formed outside thefirst area. However, in the figure, the opening portions 53A (53B) areformed to be equal to each other; however, there is no necessity offorming them to be equal to.

A size and a number of dispositions of the opening portions 53A, whichare formed in the first area beside the display region, are set to besuch degrees, that the sealing member 30 can be cured, fully, therebyobtaining a sufficient durability against an external force, such as,the sliding and/or the pressure, etc.; in other words, the opening ratiois determined to 30 to 80%, and more preferably, to 50 to 70%. If theopening ratio is smaller than 30%, the curing of the sealing materialcomes to be insufficient. A size and a number of dispositions of theopening portions 53B, which are formed in the second area, lying outerthan the first area, are set to be such degrees, that an amount of lightof the UV rays necessary for adhering or bonding the TFT substrate 10and the facing substrate 20 can be obtained, at the minimum; in otherwords, the opening ratio is determined to 5 to 50%, and more preferably,to 5 to 30%. If the opening ratio is larger than 50%, the resistance ofthe common wiring is increased. As an example, the opening ratio of theopening portion 53A in the first area beside the display region of thesealing member 30 is set to 53%, while the opening ratio of the openingportion 53B in the second area outer than the first area of the sealingmember to 8%.

For width of the first area 55A beside the display region of the openingportion 53A, it is necessary to be equal to or greater than 30%, for thepurpose of suppressing the rubbing between the column-like spacer andthe TFT wiring, so as to prevent the alignment film from being cut out,and more preferably, to be equal to or greater than 50%.

Herein, explanation will be given on the opening ratio, by referring toFIG. 9. The opening ratio is presented by a ratio of an area of theopening portion with respect to a unit of area. As is shown in FIG. 9,in case where a rectangular opening portion is provided within arectangular unit of area, the opening ratio can be presented by thefollowing equation, where assuming that width of the opening in thevertical direction is “B” and width of the wiring in the verticaldirection is “D”, and that widths of the opening and the wiring are “A”and “C” in the horizontal direction:opening ratio=(A×B)/(A+C)×(B+D)

In order to increase the opening ratio, it is enough to enlarge the areaof the opening portion, or alternately, to increase the number of theopening portions.

However, in FIG. 2, a reference numeral 70 depicts the color filter,which is provided on the facing substrate, and a reference numeral 80depicts the column-like spacer, and a reference numeral 100 depicts a BM(i.e., a black matrix), and a reference numeral 110 depicts an OC (i.e.,an over coating), respectively, while a reference numeral 90 depictsalignment films, which are formed on the TFT substrate and the facingsubstrate, respectively.

With the embodiment 1, since the opening ratio of the opening portion53A on the wiring in the first area 55A beside the display region isdetermined to be large, a ratio of passing of the UV rays is increased,on the sealing layer beside the display region; thereby encouraging thecuring of the seal. And, the opening ratio of the opening portion 53B onthe wiring in the second area 55B outer than the first area is notenlarged, the resistance of the common wiring is not increased than theenlargement of the opening ratio on the entire surface of the commonwiring. In particular, since the opening ratio is determined to be largein the first area 55A beside the display region near to the column-likespacer, etc., then the curing of the seal is accelerated on the side ofthe display region, than the enlargement of the opening ratio in thesecond area 55B outer than the first area; therefore, an amount ofdeformation of the panel is lessened. For this reason, rubbing betweenthe column-like spacer and the TFT wiring can be suppressed down, whenreceiving the external force of the sliding and/or the pressure, etc.,such as, the mechanical polishing thereon, and therefore, it is possibleto prevent the alignment film from being cut out.

In this embodiment, further, as is shown in FIG. 1, in case where widthof the common wiring 50 is wider that the width of the sealing member30, the opening portions 53A are formed also in a region (i.e., aninterior region of the sealing member) 55C where no sealing member 30 isformed beside the display region. The UV rays passing through thisregion 55C are diffused to be irradiated upon the sealing member 30, sothat an amount of irradiation of the UV rays is increased up, on theside of the display region of the sealing member 30, and thereby thecuring of the seal is encouraged or accelerated, much more.

Comparative Example

For comparison, in FIG. 5 and FIG. 6 are shown a plane view and across-section view, in case of determining the opening ratio of theopening portions 53B on the entire surface of the common wiring 50 to be8%.

In this case, the UV rays 60 are hardly irradiated upon the sealingmember 30, and due to shortage of the curing of the sealing member 30,an amount of deformation of the panel comes to large, when receiving theexternal force, such as, the sliding and/or the pressure, etc., andsince the column-like spacers 80, which are formed on the facingsubstrate 20, contact strongly on the wirings, which are formed on theTFT substrate 10, then the alignment films 90, which are formed on thesurfaces of the facing substrate 20 and the TFT substrate 10, are cutout, and there may be brought about a wear that a minute bright spot canbe generated.

Second Embodiment

A second embodiment is that, in which the opening ratio of the openingportion is enlarged, in the entire regions of the common wirings wherethey pile up on the sealing member.

FIG. 7 is an enlarged view of a panel periphery portion according to anembodiment 2, corresponding to the corner portion shown in FIG. 4. FIG.8 is also a cross-section view of the panel periphery portion of theembodiment 2, in the direction shown by an A-A′ line in FIG. 7. Withinthe panel periphery portion is formed such common wiring 50 as mentionedabove, and it lies at the position piling up the sealing member 30mentioned above. On the common wiring 50 are formed the opening portions53A, each being enlarged in the opening ratio for the UV rays 60 to passtherethrough, and thereby curing the sealing member, covering over theentire regions 55 on the sealing member 30.

A size and a number of dispositions of the opening portions 53A are setto be such degrees, that the sealing member 30 can be cured, fully,thereby obtaining a sufficient durability against an external force,such as, the sliding and/or the pressure, etc.; in other words, theopening ratio is determined to 30 to 80%, and more preferably, to 50 to70%. If the opening ratio is smaller than 30%, the curing of the sealingmember comes to be insufficient. If the opening ratio comes to be largerthan 80%, the resistance of the wiring is increased up, then there isgenerated a possibility of lowering the quality of display or breakingdown the wire, etc. As an example, the opening ratio of the openingportion 53A is determined to be 53%.

With such embodiment 2, because the opening ratio of the opening portion53A on the wiring 50 is made large all over the entire region 55 of thecommon wiring 50, piling on the sealing member 30, a transmission factorfor the UV rays is increased, and the curing of seal is accelerated. Forthis reason, rubbing between the column-like spacer and the TFT wiringcan be suppressed down, when receiving the external force of the slidingand/or the pressure, etc., such as, upon the mechanical polishingthereon, and therefore, it is possible to prevent the alignment filmsfrom being cut out.

Also, in this embodiment, as is shown in FIG. 7, in case where the widthof the common wiring 50 is wider than the width of the sealing member30, the opening portions 53A are formed also in the region (i.e., theregion inside the sealing member) 55C where no sealing member 30 isformed beside the display region. The UV rays passing through thisregion 55C are diffused to be irradiated upon the sealing member 30, sothat an amount of irradiation of the UV rays is increased up, on theside of the display region of the sealing member 30, and thereby thecuring of the seal is encouraged, much more.

According to the present invention, it is possible to manufacture theliquid crystal display device having the durability against the externalforce, i.e., the mechanical polishing, such as, the sliding and/or thepressure, etc., while suppressing an increase of the resistance of thecommon wiring. Although the explanation was given on the liquid crystaldisplay device, applying the ODF process therein; however, the presentinvention can be applied, not being restricted to that applying the ODFprocess therein, but also generally to the liquid crystal displaydevices, sealing between two pieces of the substrates by the sealingmaterial including the UV ray curable type resin therein.

The invention may be embodied in other specific forms without departingfrom the spirit or essential characteristics thereof. The presentembodiment is therefore to be considered in all respects as illustrativeand not restrictive, the scope of the invention being indicated by theappended claims, rather than by the foregoing description, and allchanges which come within the meaning and range of equivalency of theclaims are therefore intended to be embraced therein.

What is claimed is:
 1. A liquid crystal display device, comprising: aTFT substrate, having pixel electrodes and TFTs thereon in a displayregion and having a wiring comprised of a material configured forshutting off UV rays on a peripheral region thereof; a facing substrateconfigured to be disposed to face the TFT substrate; a liquid crystallayer located between the TFT substrate and the facing substrate; and asealing material, including a UV ray curable resin therein, and beingformed on peripheral regions of the both substrate, to enclose theliquid crystal layer, wherein the wiring and the sealing materialoverlap at least in part thereof in an overlapping region, the wiringextends along a direction as an extending direction of the sealingmaterial, plural numbers of opening portions are formed in the wiring inthe overlapping region, the wiring in the overlapping region has a firstarea and a second area, the first area is nearer to the display regionthan the second area, an opening ratio of the opening portions in thefirst area is different from an opening ratio of the opening portions inthe second area, the opening portions of the wiring are formed atintervals in the extending direction of the wiring, and a width of theopening portion in the extending direction of the wiring is wider than awidth of each of the intervals between the opening portions in theextending direction of the wiring.
 2. The liquid crystal display device,as described in the claim 1, wherein the opening ratio of the openingportions of the first area is 30 to 80%, while the opening ratio of theopening portions of the second area is 5 to 50%.
 3. The liquid crystaldisplay device, as described in the claim 2, wherein the opening ratioof the opening portions of the first area is 50 to 70%.
 4. The liquidcrystal display device, as described in the claim 2, wherein the openingratio of the opening portions of the second area is 5 to 30%.
 5. Theliquid crystal display device, as described in the claim 1, wherein awidth of the first area in a perpendicular direction to the extendingdirection is equal or greater than 30% with respect to a width of thesealing material in the perpendicular direction to the extendingdirection.
 6. The liquid crystal display device, as described in theclaim 1, wherein plural numbers of opening portions are formed in athird area of the wiring, wherein the third area is located between theoverlapping region and the display region.
 7. The liquid crystal displaydevice, as described in the claim 6, wherein the opening portions of thewiring are formed at intervals in the extending direction of the wiringin the third area.
 8. The liquid crystal display device, as described inthe claim 6, wherein the wiring has a fourth area between the third areaand the display region, and wherein an opening portion is not formed inthe fourth area.
 9. The liquid crystal display device, as described inthe claim 1, wherein the plural numbers of opening portions aredisposed, equally.
 10. The liquid crystal display device, as describedin the claim 1, wherein the wiring has a straight portion along a sideof the TFT substrate and a turn around portion, and the turn aroundportion has opening portions.
 11. The liquid crystal display device, asdescribed in the claim 10, wherein the straight portion has openingportions, and wherein a shape of the opening portions in the straightportion of the wiring is different from a shape of the opening portionsin the turn around portion of the wiring.
 12. The liquid crystal displaydevice, as described in the claim 1, wherein the wiring comprises acommon wiring configured to supply common electric potential to thepixel.
 13. The liquid crystal display device, as described in the claim1, wherein a width of the first area in a perpendicular direction to theextending direction is equal or greater than 50% with respect to a widthof the sealing material in the perpendicular direction to the extendingdirection.
 14. The liquid crystal display device, as described in theclaim 1, wherein an area of one of the opening portions in the firstarea is different from an area of one of the opening portions in thesecond area.